998 BIOLOGICAL EFFECTS OF RADIATION 



cultures were reported as, in general, more sensitive than older. The 

 variations induced by the radium were reported to be inherited in the 

 next generation. There was a retardation of growth, and 5 to 6 days 

 after irradiation atypical growth forms appeared. Morphological varia- 

 tions were observed, such as long, threadlike cells with the cytoplasm 

 homogeneously vacuolated and the nucleus located at the end; greatly 

 enlarged club-shaped cells ; much thickened cell walls (a protective device 

 against the radium) ; amoeboid forms ; nuclear degeneration. The normal 

 glycogen formation of Saccharomyces was inhibited, and carbohydrate 

 formation in Cryptococcus. Saccharomyces, Cryptococcus, and Nadsonia 

 formed resting cells which gave rise to normal generations. 



The structural abnormalities appeared (were "inherited") in suc- 

 cessive generations — in some races for 40 to 60 and in one race for as 

 many as 100. Such races have, by some authors, been interpreted as true 

 mutations, but since no previous alterations of the genotype had been 

 recorded for these organisms, Nadson did not call them mutations, but 

 "persisting modifications" (Dauermodifikation) . In these experiments, 

 Nadson used 5 to 10 mg. of radium bromide under thin sheets of mica. 



In a later paper, Nadson (59) reported experiments which led to the 

 conclusion that roentgen rays and the beta and gamma rays of radium 

 accelerate the tempo of life and thereby induce a premature senescence — a 

 consequence of an excess of stimulation which became, in effect, an 

 irritation. 



Kotzareff and Chodat (43) exposed yeast cultures in cider (Most), 

 by adding 0.25 millicurie of radium emanation. Budding and fermenta- 

 tion were stimulated. With a dose of 2 millicuries cell multiplication 

 was decreased and fermentation reduced one-fifth. Stronger dosage 

 (5-6 millicuries) completely inhibited fermentation and caused hyper- 

 trophy of the cells through strongly reducing their power to divide. 

 When the culture was transferred to an emanation-free medium, normal 

 growth and fermentation returned. 



Various attempts have been made to analyze the mechanism by which 

 radium rays produce their effects on living cells, tissues, and organisms. 

 Redfield and Bright (65a) investigated this problem by exposing radish 

 seeds in a dry condition to the beta and gamma rays by placing in a 

 test tube seeds "closely packed about a glass tube containing radium 

 emanation." The alpha rays were, as usual, screened out by the glass 

 walls of the emanation tube. The effect of the gamma rays was con- 

 sidered negligible owing to their limited absorption by the seed. Two 

 days after radiation the seeds were moistened and their production of 

 carbon dioxide determined. They were then given an opportunity to 

 germinate and grow. It was found that, while growth was retarded by 

 the rays, the rate of carbon dioxide production in exposed seeds was 

 invariably greater than in the unexposed control. Thus it appears that, 



